Carlstadt was originally formed as a village by an Act of the New Jersey Legislature on March 12, 1860, within Lodi Township. It was named after Dr. Carl Klein, the leader of a group of early German settlers. The Borough of Carlstadt was incorporated on June 27, 1894, formally set off from Bergen Township, at the height of the Boroughitis phenomenon then sweeping through Bergen County.
As of the census of 2000, there were 5,917 people, 2,393 households, and 1,593 families residing in the borough. The population density was 1,496.4 people per square mile (578.4/km²). There were 2,473 housing units at an average density of 625.4/sq mi (241.7/km²). The racial makeup of the borough was 88.90% White, 1.37% African American, 0.08% Native American, 6.19% Asian, 0.02% Pacific Islander, 2.13% from other races, and 1.32% from two or more races. Hispanic or Latino of any race were 7.99% of the population.
There were 2,393 households out of which 25.7% had children under the age of 18 living with them, 51.9% were married couples living together, 10.8% had a female householder with no husband present, and 33.4% were non-families. 26.4% of all households were made up of individuals and 9.6% had someone living alone who was 65 years of age or older. The average household size was 2.47 and the average family size was 3.04.
In the borough the population was spread out with 19.0% under the age of 18, 7.7% from 18 to 24, 34.0% from 25 to 44, 24.0% from 45 to 64, and 15.3% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 94.1 males. For every 100 females age 18 and over, there were 92.4 males.
The median income for a household in the borough was $55,058, and the median income for a family was $62,040. Males had a median income of $46,540 versus $36,804 for females. The per capita income for the borough was $28,713. About 3.1% of families and 6.1% of the population were below the poverty line, including 7.8% of those under age 18 and 4.3% of those age 65 or over.
New Jersey Transit bus service is available to the Port Authority Bus Terminal in Midtown Manhattan on the 161, 163 and 164 routes; to Jersey City on the 76; and to other New Jersey communities served on the 703 and 772 routes.
Route 120, County Route 503, and the western spur of the New Jersey Turnpike (Interstate 95) serve Carlstadt.